A laser scanner is an optical measuring instrument which captures measurement points in the three-dimensional space without contact. Due to the registration of a close-meshed mesh of points, complex geometries can be illustrated in a so-called point cloud. In order to register more complex objects, several measurements from various perspectives are required. In order to merge the various point clouds geometrically correct in a software for analysis, high-quality laser scanner accessories, for instance reference points (reference spheres, target marks), are required.
Fields of application of the laser scanner
Laser scanners can be used versatilely. Every time objects have to be surveyed three-dimensionally, this job can be realized by means of a 3D laser scanner. Especially in the case of very complex objects, the laser scanner has many advantages. When the object is scanned, all dimensions can be taken on the computer afterwards. Subsequently, it is possible to model the objects on the basis of the point clouds in a CAD system. Typical applications of laser scanners are for example:
- design and planning of factory buildings and digital factory
- reverse engineering
- modernization
- architecture, preservation of buildings and monuments
- mining industry and tunnel construction
- public service corporations
- aircraft construction and naval architecture
- foundries and steel industry
- chemistry and process industry
Mode of operation of a laser scanner
Laser scanners operate, as indicated by the name, with laser light. In that process, a laser beam is emitted by the scanner, then reflected by the surroundings and captured by the receiving optics. In that process, the beam is diffracted by a deflection mirror which is rotating. This process is realized several hundred thousand times per second. Then, the laser light received by the scanner is analyzed.
There are two different measurement methods for this analysis. These methods are classified according to the devices:
Laser scanner with time-of-flight (TOF) method:
During the time-of-flight method, light pulses are modeled on a carrier wave. The time between the sending and receiving by the device is measured. Based on the time-of-flight, the distance to the scanner can be determined. The advantages of the time-of-flight method are the wide ranges and the increased eye safety of these laser scanners. Thus, the strengths of the time-of-flight scanners include the scanning of wide distances.
Phase-based method:
During the phase-based method, light waves with different wavelengths are sent out by the laser scanner. Then, these different light waves are compared to each other. By means of phase shifting, the distance covered by the light beam is determined. Advantages of the phase-based method are the high measuring speed, the high accuracy and the high resolution. The method is particularly suited for scanning complex, continuous geometries at a limited range.
Laser scanner manufacturers
By now, there are various manufacturers of laser scanners. All scanners on the market have their strengths and weaknesses. Unfortunately, the individual devices cannot directly be compared to each other because the manufacturers provide different data. Furthermore, the scanner's suitability essentially depends on the scanning job. In addition, the technical development is rapid and the manufacturers introduce advanced scanners onto the market annually. Thus, statements don't stay up-to-date. As a consequence, you are reliant on an independent service provider or reseller who recommends the perfect device for the purpose to you due to his experience.
List of laser scanner manufacturers:
- Trimble Navigation Limited
- FARO EUROPE GmbH & Co. KG
- Leica Geosystems AG
- RIEGL Laser Measurement Systems GmbH
- Maptek Pty Ltd
- Basis Software, Inc.
- Topcon Europe BV.
- Optech Incorporated
- Zoller+Fröhlich GmbH
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